Well drilling apparatus



July 12, 1966 w. J. NELSON ETAL 3,250,318

WELL DRILLING APPARATUS Filed NOV. l2, 1.963

United States Patent O 3,260,318 WELL DRILLING APPARATUS William J.Neilson, Whittier, Erskine P. Garrison, Long Beach, and Gayle D. Smith,Norwalk, Calif., assignors to Smith Industries International, Inc.,Compton, Calif., a corporation of California Filed Nov. 12, 1963, Ser.No. 322,596 1 Claim. (Cl. 175-75) This invention relates to improvementsin well drilling apparatus.

Heretofore it has Abeen recognized that a number of advantages can begained in drilling Wells by employing a stationary drill pipe or drillstring which has attached at its lower end a down hole motor the rotorof which is connected to and rotates a rotary bit. In such an apparatus-a iiuid, usually a relatively incompressible liquid, is .forced downthe stationary drill pipe or drill string and on passing through thefluid-operated motor causes the rotor thereof to rotate the drillingbit. The drill string is held or suspended in such a manner that it doesnot rotate and therefore may be regarded as being stationary. However,it is lowered in the Well as drilling proceeds.

The forces required to rotate the rotary bit at the tbottom of thestring yare such that in the usual situation the fluid-operated motormust be quite lengthy. An apparatus of lthis general character is veryadvantageous in directional drilling in which case the practiceheretofore has been to position a bent sub between the top of thefluid-operated motor and the `axis of rotation of the bit to the axis ofthe dril-l pipe. However, due to the length of the motor required andother structure connecting the rotor of the motor to the bit, thespacing of the bent sub from the bit is excessive. Frequently thisdistance amounts .to approximately 22 feet or frnore which isobjectionable due to the fact that it is difficult to position and tomaintain the orientation of the bit in relation to the axis of the drillpipe. These objections in directional drilling can be largely overcomeif the bent sub could be located closer tothe bit.

The preferred type of Huid-operated. motor which we employ is a Moyn-opump which when it has circulation iluid forced therethrough functionsas a fluid-operated lmotor. The rotor of such -a pump has its lower endgyrating about the axis of its stator so that some form of universaljoint or flexible connection must be employed in establishing andmaintaining a driving connection 'between the rotor and the bit whichrotates about a stationary axis. As ia clearance must exist between thisuniversal joint or flexible connection and the walls of the surroundinghousing to accommodate the flexibility of movement, we take advantage ofthis by bending the surrounding housing for directional drilling. Inthis manner, by angularly relating the axis of rotation of the bit tonot only the axis of the drill string but also the axis of theHuid-operated motor attached thereto, we in effect locate the bent submuch closer to the bit than in the situation where the bent sub islocated between the top of the fluid-operated motor and the drillstring. Control of the bit and its orientation are consequently moreeasily obtained and maintained.

With the foregoing and other objects in view, which will be mademanifest in the following detailed description and specifically pointedout in the appended claims, reference is had to the accompanyingdrawings for an illustrative embodiment of the invention, wherein:

FIGURE l is a view in side elevation of the apparatus embodying thepresent invention, the same Ibeing shown in a well being drilledthereby.

FIG. 2 is a partial view in vertical section.

Referring to the accompanying drawings wherein similar referencecharacters designate similar parts throughout, the apparatus embodyingthe present invention con- 3,260,318 Patented July 12, 1966 sists of adrill pipe or drill string 10 which is stationary in the sense that itdoes not rotate as is the case with conventional drill pipe in aconventional rotary well drilling apparatus. This drill string leads tothe top of a fluidoperated motor generally indicated at 12 consistinggenerally -of a stator 13 within which there is rotatable or gyratable arotor 14. The fluid-operated motor which we employ is of the positivedisplacement type and preferably consists of a Moyno pump which, onhaving fluid such as well drilling fluid forced therethrough from thedrill pipe 10, will cause the rotor 14 to rotate or gyrate withsu'licient power to rotate the well drilling bit. The well drilling bitis illustrated at 15 and may be of any preferred or conventional design.This bit is rigidly connected to a rotary shaft or mandrel 16 rotatablewithin a bearing 17 in an outer -housing or drill collar 18. Suitablethrust bearings indicated at 19 and 19A may be employed as indicated tocarry the various thrust loads that may be involved. The upper end ofthe shaft or mandrel 16 is provided with ports 21 through which liquidthat is discharged through the stator 13 to drive the rotor 14 may enterthe hollow mandrel or shaft 16 and on passing therethrough be dischargedat the -bit for the purpose of lubricating t-he cutters thereof andflushing out well cuttings.

As Ithe lower end of the rotor 14 of the Huid-operated motor movesthrough a gyratory or elliptical path and the mandrel 16 to which thebit is connected rotates about an axis that is stationary with respectto the surrounding housing 18, some form of universal joint or flexibleconnection rnust be employed between the rotor 14 and the shaft 16. Thisis shown as consisting of upper and lower universal joints 20 and 20A,but other forms of flexible connections can be used in lieu thereof.

We take advantage of the fact that a universal joint or flexibleconnection must :be present between the rotor 14 and the mandrel orshaft 16 and that a clearance space 25 must exist therearound, to locatethe bent sub at this point rather than at the top of the fluid-operatedmotor 12. In other words, where the apparatus is to be used fordirectional drilling the housing 26 is so shaped or designed that its.top pin 27 and box 28 are disaligned or are angularly related to eachother. The fact that the housing 26 is thus in effect bent between itsends does not interfere with the universality or the flexibility of theflexible joint that connects the rotor 14 to the mandrel 16. With thisarrangement the location of the bend in the drilling apparatus can bequite close Ito the Ibit 15 so that in setting the direction of drillingof the bit by turning the drill pipe 10, t-he direction can beaccurately oriented. Also the proximity of the bend in housing 26 to thebit 15 facilitates the direction being maintained without a tendency ofthe `bit to Wander. FIG. 1 illustrates a situation wherein by reason ofthe angular relationship between the top and bottom of the housing 26the axis of the -bit 15 is angularly related to the axis of the drillpipe 10.

From the above described construction it will be appreciated that as thebent sub or bent housing is located between the fluid operated motor andthe Ibit rather than above the fluid-operated motor, greater control isobtainable over the direction of drilling of the bit 15. Location of thebend at this point does not interfere in any manner with the drivingconnection between the rot-or of the motor and the rbit. As a clearancemust exist between the connection and the Walls of the surroundinghousing to accommodate the universality of movement, lthis necessaryclearance is taken advantage of to locate the bend at this point whichis relatively close to the bit. While lthe invention has been describedin connection with a down hole motor that is operated by lluid forceddown the drill string, it will be readily appreciated that it is notrestricted thereto but may be used with other forms of down hole motorwhich have exible driving connections between the rotor thereof and thebit.

Various changes may 'be made in the details of the construction withoutdeparting from the spirit and scope of the invention as defined by theappended claim.

We claim:

Well drilling apparatus including a straight pipe assembly constitutinga drill string, a down hole motor comprising a housing, rotor and astator in axial alignment with the straight pipe assembly, a rotary bitbelow the motor including a bearing support therefor, a rigid bent pipesection closely connecting said. motor housing to said bit bearingsupport, and a flexible driving connection between the rotor of themotor and the bit such that the l axis of rotation of the bit isdisposed at an angle to the axis of rotation of said motor.

References Cited by the Examiner UNITED STATES PATENTS 2,500,267 3/1950Zublin 175-107 X 2,896,913 7/1959 Holmes et al. 175-75 2,898,087 8/1959Clark 175-107 X FOREIGN PATENTS 657,749 1/ 1929 France. 1,247,454 10/1960 France.

CHARLES E. OCONNELL, Primary Examiner.

R. E. FAVREAU, Assistant Examiner.

